Round Pool Volume Calculator
Calculate how many gallons a round above-ground or in-ground pool holds.
Calculator
| Liters | 51,232 L |
|---|---|
| Cubic feet | 1,810 ft³ |
| Hours to fill with a hose at 10 gal/min | 23 hours |
How it is calculated
π × (24 ÷ 2)² × 4 ft = 1,810 cubic feet × 7.48 = 13,535 gallons.
About this calculator
The volume of a round pool is π × radius² × water depth, converted to gallons by multiplying cubic feet by 7.48. An 18-foot round pool filled to 4 feet holds about 7,600 gallons.
Use the depth of the water, not the height of the wall, and remember that the manufacturer's stated capacity assumes a specific water level. Knowing the volume helps you dose chemicals correctly.
Worked examples
| Project | US gallons | Rough cost |
|---|---|---|
| a 12 ft round pool with water 3 ft deep | 2,538 gal | $10.15 – $30.45 |
| a 18 ft round pool with water 4 ft deep | 7,614 gal | $30.45 – $91.36 |
| a 24 ft round pool with water 4 ft deep | 13,535 gal | $54.14 – $162 |
| a 30 ft round pool with water 4.5 ft deep | 23,793 gal | $95.17 – $286 |
Buying notes
- Measure the diameter inside the pool wall.
- The fill time shown assumes about 10 gallons per minute from a hose; real flow varies.
- Check your pool's manual for its recommended water level.
Quick answers by size
Click a size for the exact quantity and cost.
How to measure and use this calculator
- Measure the pool's diameter across the middle.
- Measure the water depth, not the wall height.
- Read gallons and fill time.
- Use the volume to dose chemicals.
Common mistakes
- Using the outside wall diameter when the inside is smaller.
- Using wall height when the water is lower.
- Forgetting the volume changes when the water level changes.
Tips
- Use the actual water depth rather than the wall height.
- Manufacturers' rated capacities are usually for water filled to a given line; yours may differ.
- Use the volume to dose chemicals correctly.
Frequently asked questions
How many gallons in a 24-foot round pool?
About 11,800 gallons at 3.5 ft of water depth and about 13,500 gallons at 4 ft.
How many gallons are in an 18-foot round pool?
About 7,600 gallons at 4 feet of water depth.
How do I find the volume of a round pool?
Multiply π by the radius squared and by the water depth in feet, then by 7.48 to get gallons.